Our Average Body Temperature Is Dropping And Scientists Don’t Know Why
The human body normally runs at a very specific temperature, but that temperature is getting colder, and scientists aren’t quite sure why.
A study by the University of California in Santa Barbara has found that over the past two centuries, our average body temperature has dropped, in some cases by more than half a degree. That might not seem like much, but given that a normal healthy temperature only sits within about a one degree range, it’s a significant change, and has left scientists stumped for an explanation.
In the 19th century, German physician Carl Wunderlich established that the average healthy human body temperature was 37°C. In the years since, the number has been generally accepted as 36.8, with a healthy range typically viewed as anywhere between 36.5-37.8.
But now, a study has found that in the United States, the average body temperature has dropped to 36.6°C, while in the UK, it has fallen below the lower end of the accepted healthy range to 36.3.
An even more stark change was observed in more remote areas of the world; the Tsimane indigenous tribe in the Amazon has seen the average body temperature of its people drop by a similar level within just twenty years.
A number of theories have emerged over the years about what could cause these changes in temperature. Some believe that a general improvement in human health, through things like cleaner water and vaccinations, has reduced infections that cause higher temperatures. Others have suggested that widespread use of air conditioning and heating means that the human body no longer has to work as hard to regulate its own temperature.
But the new observations about the Tsimane would seem to disprove both these theories. The tribe doesn’t have air con, or access to the same healthcare as those in the western world, yet has still experienced a similar drop in temperature.
Anthropologist and study co-author Michael Gurven acknowledged that there was no ‘magic bullet’ explaining the changes, and said that the readings did not necessarily mean populations were getting less healthy.
It’s likely a combination of factors — all pointing to improved conditions.
One thing we’ve known for a while is that there is no universal ‘normal’ body temperature for everyone at all times, so I doubt our findings will affect how clinicians use body temperature readings in practice.
While the study is not going to lead to widespread changes in how we determine health or illness, analysing these kind of changes could help scientists learn more about how the overall health of different populations is changing over time.
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